Process of treating ores.



PATENTED OCT. 30, 1906.

P. T. SNYDER.

PROCESS OF TREATING ORES. urmoumn FILED 111111121, 1905.

3 SHEETS-SHEET 1- Jrzr/ezz 6Z1" T w ww m 110,834,644. PATENTED 0013.30, 1906.

' F. T. SNYDER.

PROCESS OF TREATING ORES.

APPLICATION FILED JUNE 21,1906.

3'BHEETSSEBET 2.

No. 834.644. PATENTED OCT. 30, 1906.

F.T.SNYDBR. PROCESS OF TREATING 035s.

APPLICATION FILED JUNE 21,1906.

3 SHEETS-SHEET 3.

i To all whom it may concern.-

UNITED v STATES PATENT OFFICE.

FREDERICK T. SNYDER, OF OAK PARK. ILLINOIS. Pnocsss OF TREATING ones.

' containing metallic compounds which are rewith carbon in the In practicin product while commercially a f the zinc the temperature tamed at a point such that a part of the lead duced at different temperatures, the object being the. reduction of t ese compounds with reat econo mv of heat and to produce the ifl'erent :uzeta s in as pure a. state as ossible. The invention is particularly ap hcable to zinc-lead ores and makes it possl le to extract substantially all the zinc and leadin a single smelting operation, while obtainin the zinc in metalllc orm substantially free om lead. In other applications,- Serial Nos. 266,540 and 266,541, filed June 23, 1905, I have described methods of treating such ores involving the use of an electric furnace from which air 'is excluded, the ore being smelted furnace to reduce both the zinc and lead, the lead being collected in liquid form, while the zinc is volatilized and condensed or otherwise separately collected.

the processes of my a plications above re erred to I found that t e zinc ood contained a considerable proportion of lead. This I found was due to the fact that in order to obtain as near as possible com lete reduction of has to be mainwould be volatilized and carried over with the zinc-vapor into the condensing-chamber. My present invention involves developing in a body- .of ore in the presence of carbon a graduated heat sufficient to reduce the different constituents of the ore at different places ment of lead-zinc ores, for,

i-jfhaving kbeen crushed and in the ore body and rogressively advancin the place of increase they are thus serially reduced. In the treatexample, the profollows: The ore preferably oxids and cedure is substantially as roasted to convert the sulfids into to drive out all gases so far as possible, is

mixed with crushed carbon, preferably in the form. of coke. or-r'lean'coal, (and with slag-,

Specification of Letters Patent. Application filed June 21,1906. Seriallo. aeaaoa.

I the lead, but will con sistance of the conductor; In the case of the i Patented Oct. 80, 1906.

forming the ore,) and the mixture is then ed onto a heat is developed intemall by the passage of an electric current. The eat in the furnace is graduated, so that in one part thereof it will be suflicient merely to start the reduction of 0 r0 essively increased to a point considerabl; ai ove the volatilization temperature of zinc at anotherportion.

materials already resent in I The ore being fed into the furnace at the cooler portion thereof is progressively advanced toward the place of increased temperature. In its advance the lead is first reduced and is allowed to settle out below the ore body before the latter is advanced to a place at which an the lead would vo atilize. Finally, the residue, from which practically all the lead has settled out, is pushed on toward the hotter part of the furnace, where the reduction will e completed the zinc being thoroughly the ore and slag by intense heat,

driven out of while the lead previously reduced has been conducted away from the hottest part of the furnace and is protected from the more intense heat by the body of ore and slag above it.

I have found that the'desired graduated tern erature in the furnacecan be convenient y slag o graduated depth and. assing the electric current directly throug the slag between the deeper and shallower portions thereof. The degree of heat produced by the (passage of an electric current through a uctor depends,.of course, upon the reslag the cross-section gradually decreases toward one end, so that the heat developed by the passage of the current will naturall be eatest in that portion of the sl whic is o smallest cross-section. The lea which is reduced and settles out below the ore body naturally tends to flowtoward the doc est,

portion of the furnace, so that as fast as It is reduced it is thus conducted away from the greatest heat. The temperature at which the zinc is reduced, however, is so high that the zinc is immediately volatilized, and the separate chamber. The heat developed in the shallowest portion of the slag is sufficiently intense, so that the residues advanced to this part of the furnace will be very considerable quantity of roduced by maintaining a body of ,vapor may. be'collected and condensed in a IIO thoroughly reduced" and substantially all' the zinc-vapor driven off and boiled out of the sla It will be seen that this process is economical of heat, for the reason that instead of requiring the whole body of ore to be heated to a temperature'far above that at which some of t e metals are reduced it is heated first only to a temperature at which one of the metals is reduced and only the residue is necessarily subjected to the greatest heat required for reducing the remaining metals; but probably the most important advantage of the process in the treatment of leadzinc ores is that the zinc roduct is obtained direct from the smefting operation substantially free from lead, so that it does not have to be refined in order to put it in marketable condition.

A furnace suitable forthe ractice of my improved process is illustrated in the accompanying drawings.

Figure 1 is a sectional elevation of the furnace. Fig. 2 is a transverse sectional view on line 2 2 of Fig. 3. Fig. 3 is a sectional plan view on line 3 3 of Fig. 1.

The same letters of reference designate the same parts wherever they are shown.

In the furnace shown the-smeltingcham ber a is constructed with thick walls I) b, of

. refractory material, a reverberatory roof 0,

and a sloping hearth d, havin a deep well 6 at one end. Carbon electrodes f project down through the roof of the sme ting-chamber above the upper end of the sloping hearth in position to di into the shallower portion of the molten s ag in the chamber, which will be kept substantially at the level indicated. The well e at the op osite end of the chamber will contain moften lead .to serve as another electrode. This well e communicates with the exterior of the furnace by U-shaped passages, into the outer arms of which conductin -rods 9 are dipped. The rods g and the ro s f are connected, respectively, with the terminals of an electric generator G, so that the current from said generator will molten slag in the nae between the leadwell 0 and the carbon electrodes ff. As the cross-section of the body of molten material in the furnace is radually reduced toward the upper end of t e hearth and as the slag at the top is of hi her resistance than the molten lead, it be seen that the heat will be developed at the highest degree near the electrodes f f, where the slag-bath is of least depth, and will be gradually diminished in intensity toward the opposite end of the furnace.

It is intended that the ore shall be introduced at the rear of the furnace, where the heat is less intense, and a charging door or tube 7c opens through the rear wall of the furnace above the lead-well e for this purfurnace can be ass through the body of pose. The charging-tube is constructed with an inclined branch 1, into the up er end of which the ore is introduced and t irough which it passes to the main charging-tube k. The ore in the tube is and the rear end of the ushed forward from time to time by a suitable rod or pusher introduced throu h the outer end m of the tube. The charging-tubes We are supported in a furnacechamber 1, provided at the bottom with a fire-grate 0 and at the top with a stack p and an openin q, through which fuel may be introduced. mixed with crushed carbon, shall be preheated in the charging-tubes l k by heat developed. from the combustion of fuel in the chamber n to start the process of reduction so far as possible without the use of the more costly electrical heat, the latter being then required only for the actual smelting operation. Atap-hole 1" is provided in the wall of the smeltingchamber, through which the surplus slag may be removed from time to time. This tap-hole is normally stopped by a clay plug.

Flues s 8 lead through the side walls of the furnace to conduct away the zinc-Va or, and, as shown, these flues end in cham ers t t, which, together with said flues, serve as con' densers. Flues u it lead away from the tops of chambers t t to carry off the uncondensed gases. As shown, the fines and condensers may be conveniently formed of tiling. The condensers are shown as formed of a T-joint tile, the outer end being closed with a disk or blank '12, which may be removed, if desired, to allow the interior to be cleaned from incrustations or collections of zinc-dust. The blank 1) is provided with a tap-hole w at the bottom, normally closed by a clay plug.

In the operation of the furnace the ore, which has been crushed and referably roasted, is mixed with carbon, a so crushed, and fed into the mouth of the inclined chargingtube 1, from which it is gradually fed into the furnace by pushing it with a rod introduced through the tube k. The tubes Z and k being filled with the material, no appreciable amount of air will enter the furnace during the charging operation. The ore in the ch argingtubes 1 and k is heated by the combustion of fuel in the furnace-chamber n to start the process of reduction as far as possible, and so to economize the more costly electrical heat required in'the actual smelting operation, the limit to the preheating being that slag must not be for-med in the charging-tubes, as this would quickly destroy them. As the ore is advanced into the smelting-chamber a the lead is first reduced and settles out below the body of ore and slag, running down the sloping hearth into the well e. The ore nearest the heat is first fused, and the unreduced portions thereof are gradually advanced by thet is intended that the ore,

.grade.- A thirty per iron oxid, and forty er cent. of silica'(or their respective equiva ents) willhave the dea sufficiently hi h temperature so that the zinc is condense in liquid form and collects at the bottom ,ofthe chambers. -t, from which it may be removed from time to time through the ta -.hole 10. Airshould be carefully excludeci from the furnace and from the condcnsers at all times to prevent burning of the Z1110. be maintained at about 1,200.centi ads or more in the hottest portion ofthe nace, being gradually reduced in degree toward the other end, at which the ore enters, where it will be materially less. The temperature will of course be varied, however, to meet the particular conditions of the furnace and of the ore bein treated. As to the electrical conditions I fiave found that for a small furnace a current of seven hundred and fifty or one thousand amperes at an electromotive force between the terminals of the furnace of one hundred and. fift to two hundred vo'lts gave good results. nace charge should be proportioned so as to produce a slag'which w1ll form at a temperature of approximately 1,000 or 1,100 centicent. of lime, thirtyper cent. of

siredfcharac'ter. The tendency of zinc oxid to dissolve in the slag may be overcome by having the slag high in lime; Burnt lime shoul .be used in the smelting rather than limestone to avoid the excess of gas, which-would tend'to dilute the zinc-vapor so that it would not condense in liquid form,

but as zinc-dust. While I have described this process particularly with respect to the treatment of zinclead ores, for which it is especially intended,

it will be evident that the invention herein set forth may be availed of in the treatment of other oresl a 4 I therefore claimi 1. The process of treating mixtures of ores which are reduced at different tern eratures,

at such higher temperature.

'which'co'nsists in subjecting a be y of such ores, mixed with reducing material, to a graduated heat sufiicient to reduce the different metallic constituents thereof at different places in the ore body, collectin in a'place of ower temperature the metal re need at such tem erature, progressively advancing the resi ueof the ore freed from such re uced metal to the lace of increased tem erature, and separate ycollecting the meta reduced The temperature in the furnace should I he materials of the furslag containing approximately siderable quantity of lead.

2. 'The processof treating mixtures of ores which are reduced at different tern eratures,

the ore body, collectingl in molten condition the metal reduced a as the same is reduce ing the residues, comprising the more refrac- -to constituents of the mixture freed from e lower temperature sai first-reduced ore, to a place of.greatly-' increased heat, there reducing and volatilizing said refractory constituents, and separately collecting said volatilized metal.

,1; progressively advanc 3. The process of treating mixtures of ores which reduce. at different tern eratures, which consists in advancing a be y of such ores mixed with carbon laterally across a furnace, maintaining in the furnace a tempera- .ture gradual] increasing in the direction of advance, oft e ore and sufiicient to reduce the constituents thereof one after another,

collecting the'metal first reduced in, the place of lower temperature, the unred'uced resldues onlz beingadvanced and subjected to the big e r temperature, and se arately collecting the metal reduced at suc higher temperature. 1

4. 'The process of treating zinc-lead ores which consists in, developing in a body of such ores, in the presence of carbon, and in the absence of air, a graduated heat suflicient to'reduce the lead and zinc at different places in the ore body, collecting'the lead in a place of decreased temperature underneath that portion of ore body when the reduction of said lead takes lace, pro ressively advancing the portions of the ore cm which the-lead has settled out to a place of greatly-increased temperature while retaining said reduced lead in the place of lower temperature, there reducing'and volatilizing the zinc, and separately collecting the zinc-vapor whereby the' metallic zinc may be thoroughly extracted from the ore and recovered, without carrying with it any material proportion of lead.

'5. The process of treating ores containing inc, and lead, which consists in feeding said.

ores with carbon into an electric furnace from which air is excluded, reducing from the ore body first the lead and laterthe zinc, by heat maintained electrically in progressively-1ncreasing intensity as the ore-body, is ad vanced, the ore. finally reachinga. point where the tem erature is maintained well above the volatilization temperature of zmc,

and removing the reduced lead from the ore body in a direction away from the place of increased heat, while advancing the remain- 'der of the ore body toward the place of substantially all lncreased heat; whereby e the zinc .may be vaporized and separately collected without carrying with it anyconferent constituents of the ore one after an-Iv other as the ore is advanced.

7. The process of treating ores containing metallic constituents reducing at c if'ferent temperatures, which consists in maintaining a bath of slag of graduated depth, fee .ing said ores mixed with carbon and with slagforming materials upon said slag-bath at the deeper portion thereof, gradually advancing said ore toward the shallower ortion of said slag-bath, and passing an e ectric current through said slag to maintain therein a graduated temperature progressively increasing in intensity toward the shallower portion thereof and sufficient in degree to reduce the constituents of the ore one after another as the ore is advanced, said heat being sufficient at the shallower portion of the slagto volatilize the metal last reduced and to thoroughly drive the same out of the slag; the metal first reduced being collected below the deeper end of the slag-bath.

8. The process of treating zinc-lead ores which consists in electrically developing in a body of such ores mixed with carbon, in the absence of air, a graduated heat suflicient to reduce thelead and' the zinc at different places in the ore body, collecting the lead in molten condition as it is reduced, progressively advancingr the residue of the ore substantially free creased temperature, and there reducing and volatilizing the zinc while retaining the lead in the lower temperature, and separately collecting the zinc-vapor.

9. The process of treating-ores containing both zinc and lead compounds, which consists in heating a body of such ore with carbon in the absence of air to a temperature at which the lead will be reduced, collecting and removing the reduced lead, and progress-- ively advancin the residue of the ore freed from lead to a p ace of increased temperature sufficient to reduce the zinc, and separately collecting said zinc In witness whereof I hereunto subscribe my name this 19th day of June, .A. D. 1905. FREDERICK T. SNYDER.

Witnesses:

DE Wrr'r C. TANNER, ALFRED H. MOORE.

om lead, to the place of in- 

